Muffler



Oct., 24, 1933. Q, G. Noam-'r er m.

MUFFLER Filed March l2, 1932 Patented Oct. 24, 1933 UNITED sTATl-:s

PATENT OFFICE MUFFLER poration of Indiana lApplication March 12, 1932. Serial No. 598,362

. 5 Claims. (Cl. 137-160) Our invention is concerned with muiilers for silencing the noise of flowing gases, and especially with muiiiers for use in silencing the exhaust gases of an automobile or other internal combustion engine. Our invention is especially concerned with muiiiers o! the general type illustrated and described in the co-pending applications of Q. G. Noblitt, Serial No. 519,380 and of Q. G. Nublitt, ETC. Booth, and E.Lud1ow, serial No. 554,723.

It is the object of our invention to construct a muffler which, while obtaining all the silencing eiiiciency of the muiliers described in the copending applications just referred to, will be 'shorter and more compact, and therefore of wider applicability. A further object of our invention is to simplify the construction of and lessen the vcost of muiiiers. Still another object of our invention is to produce a muiller which will prove sturdy and durable in use.

The muillers of the prior applications .above referred to comprise relatively long and substantiallystraight tubes which are enclosed in a surrounding casing and which are provided at a multiplicity of `points along their lengths with openings providing restricted communication between the interior of the tubes and the space surrounding them. In carrying out our invention we use this same general principle; but instead of employing a tube which provides a substantially straight passage through the muiiier from the inlet to the discharge thereof, we provide within the casing a pluralityof tubes and interconnect ,them in such a way that the gases flow back and forth through the'tubes within the muiiler casing. We divide the interioxLof the muii'ler casing by longitudinal partitions in order that the space surrounding each tube will be separated from the space surrounding every other tube; and in addi- (tion, we may provide, as in the prior applications above reterredto, transverse partitions for divid- 'ing into separate chambers the space surrounding the tube. 1

The accompanying drawing illustrates our invention: Fig. 1 is a longitudinal section through a muffler on the line 1-1 oi.' Fig. 3, with parts o1' the mufiler broken away; Fig. 2 is an end eleivation oi' the muilier; and Fig. `3 is a transverse :section on the line 3-.3 of Fig. 1.

The muiiier illustrated in the drawing has a cylindrical casing 10 provided with heads 1 1 and 12 at its ends. Preferably, the casing is doublewalled, the space between the walls being iilled A.with a layer of asbestos or other heating insulating material to prevent radiation' ol heat and also to prevent or deaden shell noise.

Within the casing and near the ends thereof,

Ibut spaced from the respectively adjacent heads,

three such tubes, 15, 16, and 17, are employed.

Each of these tubes is showh as substantially similr to the tube employed in the muiiler shown in co-pending application Serial No. 554,723 above referred to and comprises two similar sheet-metal stampings which i'orm the tube when juxtaposed and secured together.' Each of the tubes is provided throughout substantially its entire length fwith a series of louvers 18 which provide restricted communication between the interior oi the tube and the space surrounding it.

At the inlet end of the muiiler one of the tubes, shown as the tube 15, communicates with an inlet iitting 19 which extends through the chamber between the head 11 and partition 13 and which serves to direct all gases supplied to the muier into the tube 15 with which it is connected. Another of the tubesrshown as the tube 16 in Fig. 1, communicates with a discharge fitting 20 Iwhich extends through the chamber between the head l2 and the partition 14. The third tube. or tube 17, merely allor-ds communication between the two chambers at the ends of the muiller. As a result ,of the arrangement described, gases entering the muiiier through the inlet tting 19 are directed to the tube v15 shown at the bottom of Fig. 3 through which they pass to the chainber at the discharge end of the muiiier. Flowing .through this chamber, the gases enter the tube 17 and pass through it to the` chamber at the inlet end oi! themuiiler. From this chamber, the gases flow through the tube 16 at the top of Fig. 1 to the discharge fitting 20, through which they escape.

Extending between the transverse partitions 13 and 14 we provide longitudinal partitions 22, 23, and 24. 1n transverse cross-section, these partitions are generally radial and divide the interior of the'muiiier between the transverse partitions 13 and 14 into three substantially similar portions of generally sector-shaped cross-section, asis clear from Fig. 3. Preferably, these longitudinal partitions are not plane but are, curved laterally, as shown in Fig. 3, to provide for their sov expansion and contraction in response to temperature changes.

We may provide transverse auxiliary partitions 26 serving to divide the space surrounding each of the silencing tubes into separate portions. It is not essential that the auxiliary partitions 26 be imperforate or t the tubes 15 substantially close to prevent all possibility of gas-flow from the space on one side of a partition to the space on the other side. It is only sufficient that the auxiliary partitions serve to prevent unrestricted gas ow from one end of the muffler to the other in the spaces surrounding the tubes.

The silencing action of a muffler embodying louvered silencing tubes has been described in the copending application above referred to, and need not be'repeated here. It is sufficient to say that the interiors of the silencing tubes are unobstructed and provide for unimpeded flow of the exhaust gases from the inlet of the muffler to the discharge end thereof. The restricted communication provided by the louvers 18 between the interior of each tube and the space surrounding it provides for the smoothing out of any inequalities in pressure and the effective silencing of exhaust noise,

The whole muffler, as is clear from the drawing, is of sheet-metal. The inner and outer walls of the muffler are each composed of a single piece of sheet-metal rolled into cylindrical form and having its edges secured together with a lock seam. The heads 11 and 12, the end partitions 13 and 14, and the auxiliary partitions 26 are provided with peripheral flanges which may be spot-welded to the casing. Each of the holes in the heads 11 and 12 and in the partitions 13 and 14, which holes receive gas-conveying tubes, is provided around its periphery with an annular flange that closely surrounds the associated tube and may be spot-welded thereto.

The longitudinally extending partitions 22 are formed of sections extending respectively between adjacent transverse partitions of the muffler. Preferably, in each of the compartments into which the transverse partitions divide the muffler two of the Aiartition-sections 22 are formed of a single sheet-metal stamping while the third partition-section is formed of another sheet-metal stamping, as is clear from Fig. 3. The outer edges of the partition-sections 22 are bent to provide circumferentially extending flanges which are secured in place in the muffler casing by spotwelding.

We find that the silencing action of the muffler may be bettered by spacing the auxiliary transverse partitions 26 unequally, and therefore prefer to so space them. We also prefer to arrange the tube 15 so that its louvers slope outwardly in the direction of gas-flow through it and the tube 16 so that its louvers slope inwardly in the direction of gas-flow through it.

As a specific example of an embodiment of our invention, we may set forth the dimensions of a specific muffler found suitable for use with the' engine of the present Plymouth automobile.

In such a muler, the casing was 18 inches in length and had an internal diameter of 6 inches. The tubes l5, 16, and 17 were each 1% inches in diameter. Three of the auxiliary partitions 26 were employed, as shown in the drawing, these partitions being arranged so that their spacing was slightly uneven, as above set forth. The louvers of the tubes 15, 16, and 17 were bent out far enough to provide openings approximately 0.030 inch in width.

We find that an important dimension in the construction of mufflers of the type described is the dimension between the end of each of the tubes 15, 16, and 17 where it communicates with a chamber at one end of the muffler and the adjacent muffler-head 11 or 12. In the specific muffler above described, we make this dimension approximately 1/2 inches, or approximately onefourth the internal diameter of the muffler casing. We find that with such a spacing between the ends of the tubes 15, 16, and 17 and the adjacent head at the end of the muffler the back pressure which the muffler creates is even less than that created when the louvered tubes through which the gases successively flow are interconnected by smoothly curved conduits. For best results, the distance between the ends of the tubes and the adjacent heads is preferably not less than one-fifth the internal diameter of the muffler casing and should not be less than one-sixth of such diameter.

Our muffler is not to be confused with a muffler such as is shown in the Mason Patent No. 1,874,326 and which demands for maximum silencing efflcicncy that the openings in the metal tube be arranged in spaced groups with a section of unperforated tube separating adjacent groups. To distinguish from such a muffler, we refer in the claims to our central tubes as being provided with a continuous series of openings".

We claim as our invention:

1. A muffler, comprising a cylindrical casing having heads closing its ends, a transverse partition located within said casing near each end thereof and spaced from the adjacent head to provide a chamber, three tubes extending through said muffler between said partitions, each of said tubes having openings affording at a multiplicity of points along its length restricted communication between its interior and the space surrounding it, an inlet conduit communicating with one end of one of said tubes and extending through the adjacent chamber to a point outside the muffler, a discharge conduit communicating with another of said tubes at the opposite end of the muffler and extending through the adjacent chamber to a point outside the muffler, transverse auxiliary partitions dividing into sections the space between the said first named partitions, and three longitudinally extending partitions defining separate longitudinally extending chambers in each of which one of said tubes is located, said longitudinal partitions, in cross-section, extending generally radially of the muffler casing but being bowed out of a radial plane.

2. A muffler, comprising a cylindrical casing having heads closing its ends, a transverse partition located within said casing near each end thereof and spaced from the adjacent head to provide a chamber, three tubes extending through said muffler between said partitions, each of said tubes having openings affording at a multiplicity of points along its length restricted communication between its interior and the space surrounding it, an inlet conduit communicating with one end of one of said tubes and extending through the adjacent chamber to a point outside the muffler, a discharge conduit communicating with another of said tubes at the opposite end of the muffler and extending through the adjacent chamber to a point outside the muffler, and three longitudinally extending partitions defining separate longitudinally extending chambers in each of which one of said tubes is located, said longitudinal. partitions, in cross-section, extending :sol

generally radially of the muiiler casing but being bowed out of a radial plane.

3. A muiier, comprising a cylindrical casing having heads closing its ends, a transverse parti tion located within said casing near each end. thereof and spaced from the adjacent head to provide a chamber, three tubes extending through said rnutlier between said partitions, each of said tubes having openings affording at a multiplicity of points along its length restricted communication between its interior and the space surrounding it, an inlet conduit communicating with one end of one of said tubes and extending through the adjacent chamber to a point outside the muffler, a discharge conduit communicating with another of said tubes at the opposite end of the muffler and extending through the adjacent chamber to a point outside the muiller, partitions providing within said casing three longitudinally extending compartments in each of which one of said tubes is located, and one or more transverse partitions located within at least one of said compartments in the space between the walls of such compartment and the tube therein.

4. A muffler, comprising a casing, spaced transu verse partitions in said casing, three longitudinally co-extensive tubes located Within said casing and extending between and through said transverse partitions, longitudinal partition means extending between said transverse partitions and providing within the casing three longitudinally extending compartments in each of which one of said tubes is located, each of said tubes having within its associated compartment a continuous series of openings affording at a multiplicity of points along its length restricted communication between the interior of the tube and the compartment in which it is located, means located between said transverse partitions and in the space between each tube and the walls of its associated compartment for preventing any substantial flow of gases longitudinally through such space and for localizing pressure-variations therein, one of said tubes being adapted at one end for connection to an inlet conduit, gas-conveying means connecting the opposite end oi' said tube with the adjacent end of a second tube, and a second gas-conveying means connecting the opposite end of said second tube with the adjacent end of the third tube.

5. A muffler, comprising a casing, spaced transverse partitions in said casing, three longitudinali 1y co-extensive tubes located within said casing and extending between and through said transI verse partitions, longitudinal partition means ex tending between said transverse partitions and providing within the casing three longitudinally extending compartments in each of which one of said tubes is located, each of said tubes having within its associated compartment a continuous series of openings affording at a multiplicity of points along its length restricted communication between the interior of the tube and the compartment in which. it is located, one or more intermediate transverse partitions located within at least one of said compartments in the space between the walls of such compartment and the tube therein, one of said tubes being adapted at one end for connection to an inlet conduit, gasconveying means connecting the opposite end of said tube with the adjacent end of a second tube, and a second gas-conveying means connecting the opposite end of said second tube with the ad jacent end of the third tube.

QUIN'I'IN G. NOBLTIT. EDMU'ND LUDLOW. 

